Catalysts for the addition polymerization of unsaturated organic compounds



Patented July 31, 1945 UNITED STATES P TENT bl-i-ICE v was: CATALYQTB mm m ADDITION Palm- IZATION COMPOUNDS William D. Stewart,

8. F. Goodrl No Drawing.

'rm ORGANIC ohm-magnum Akron, ch Company, New York. N. Y, a corporation of New York Application February is, 1941,

Serial No. $10.11: 20 Claims. (cl. zoo-sun This'invention relates to the polymerization of unsaturated organic compounds which are capable of undergoing an addition polymerisation to form-high molecular weight linear polymers. more particularly to the polymerization of conjugated butadienes'either alone, in mixtures with one another or with other polymerizable comonomers such as the vinyl and vinylidene compounds. The principal object of the invention is to provide a new class of catalysts-or accelerators of polymerization by the use of which improved polymers may be obtained in increased yield and in a much shorter interval of time.

It is known that addition polymerizations may be accelerated or promoted by the presence of various substances among which are oxygen and oxygen yielding compounds such as hydrogen peroxide, benzoyl peroxide and persalts. However, with the use of such known polymerization initiators, considerable difllculty is still experienced in obtaining high yields of a desirable polymer in a short interval of time. Particularly in the commercial manufacture of polymers by emulsion polymerization, the production schedule is frequently disrupted by slow reactions and long induction periods before the polymerization starts. r

I have now discovered a large number of substances which have been termed redox systems because of their property of catalyzing or promoting oxidation reduction reactions, particularly those occurring in biological processes, which substances are quite eifective in promoting addition polymerizations and which are vastly superior to any previously described polymerization initiators or accelerators in that long periods of a periodic table arranged in short and long periods, and especially those occurring in the 8th to 12th positions of the long periods (considering the alkali metals to occupy the first position and all the rare earth metals to occupy s single position), that is, the metallic elements Periodic Table such as copper, silver, zinc, cadmium and mercury and those in subgroup A of groups VI and VII of the Mendeleef Periodic Table such as chromium, manganese and molybdenu'm. By the term derivative of a phosphorus oxyacid is included both the inorganic salts of phosphorus oxyacids such as the, alkali, alkaline earth or heavy metal ortho phosphates, pyrometaphosphates, tetraphosphates, orthophosphites, hypophosphites, metaphosphites and pyrophosphites, and the organic esters formed by the esteriiication of an organic compound containing an esteriflable hydroxy group with a phosphorus oxyacid such as the phosphates or pyrophosphates of 1 alcohols, glycols,and sugars, the nucleic acids and the phospholipids. In further clarification *of the class of redoxsystems designated as "derivatives of phosphorus oxyacids combined with a water-soluble heavy metal salt" it is to be pointed out that this expression includes both complex compoundsin which the heavy metal I and the phosphorus oxyacid derivative or resithe polymerization is carried out in a much shorter time, the induction period is largely eliminated, lower temperatures for the polymerization may be employed and consequently a vmerits which have a density greater than four,

an atomic weight greater than forty and a low atomic volume -(ratio of atomic weight to density).-and consequently appear substantially at the minimum points above an atomic weight of istry such as Ephraim Textbook of inorganic- Chemistry" p. 30 or Caven and Lander "Systematic Inorganic Chemistry facing p. 30).

The term heavy metal" includes therefore those metals appearing in the center positions of the The term "heavy metal" as used forty on Lothar Meyer's curve of atomic volumes (see any standard text book of Inorganic Chemdue are contained in the same molecule, for example, the complex salt sodium ferri pyrophosphate, and also mixtures of the phosphorus containing compound and another compound containing the heavy metal which may not interact to give a complex, for example, a mixture of ferrous sulfate and sodium hypophosphite or a mixture of ferrous sulfate and glycerine monophosphate. As specific examples of redox systems coming within this definition there may be mentioned thedollowing preferred compounds and mixtures:

Ferric pyrophosphate Sodium ferro pyrophosphate Sodium ferri pyrophosphate Sodium cupro pyrophosphate Sodium ferro triphosphai'e Potassium cobalt triphosphate Fructose di phosphoric acid-ferrous sulfate Alpha fructose-G-monophosphoric acid-cuprous chloride Phosphoglyceric acid-cobaltous chloride Lecithin-Ferric sulfate v merization process, which is at present preferred,

the monomer or monomer mixture is emulsified in a non-solvent liquid, usually water, with the aid of an emulsifying agent and poLvmerization is then effected by adding a redox system 'of this invention together, if desired, with various other substances the nature of which will be described hereinafter, and agitating the emulsion until polymer is formed. The resulting polymerized emulsion containing polymer particles dispersed in a liquid medium greatly resembles natural rubber latex and may be coagulated in the usual manner to yield the solid polymer.

The choice' of the particular redox system to be employed in carrying out any given polymerization will depend upon a number of factors including the character or the substances being polymerized, the method oi polymerization being used, and the nature of the other. ingredients present in the polymerization mixture.' Since it is believed that the function of the redox system is to facilitate or catalyze an oxidation reduction reaction which oxidizes or activates monomer molecules to such an extent that they are then capable oi initiating a chain reaction which produces a high molecular weight linear polymer, it is desirable that the redox system" employed be capable pf most fav biy exercising this function. Analogies with b ological systems in which redox catalysts are known to exert a similariunction in promoting biological oxidoreduction's have proved of great value in this connection. For example, sodium i'erri pyrophosphate is a well known catalyst for the oxidation 01' carbo-' hydrates, and the hexose phosphates inpresence of traces of a heavy metal are quite important in the conversion of sugars to glycogen or in the oxidative breakdown of hexoses in respiration. Although the choice of the particular redox systems to be used with various polymerization recipes will be more apparent after a discussion of the other ingredients present in the polymerization mixture, in general, it may be said that the complex salts containing a heavy metal occurring in the 6th to 12th positions of the first long period oi the periodic table particularly iron, cobalt and copper, and a pyrophosphate radical, such as sodium ferri pyrophosphate, sodium cupro pyrophosphate or a mixture of sodium pyrophosphate and ferric pyrophosphate, are to be preferred for most polymerizations because they are economical to obtain and also are soluble in the ordinary mers, are needed and in most instances the poly- 'merization proceeds most rapidly-when from .5

to 1% of the redox system is present. when using redox systems containing some heavy metals particularly copper, and manganese, however. it is desirable to use even smaller-amounts, less 5%, and preferably about 0.01%, since containing a s,sso,4va

cn|==c group, monomer mixtures of two or more of butadienes such as a mixture of butadiene and dimethyl butadiene, and monomer mixtures of conjugated butadienes with one or more other compounds which also contain a group and whichcopolymerize with butadienes such as the vinyl compounds including aryl olefins and substituted aryi oleflns such as styrene. p-chloro styrene, p-methoxy styrene, vinyl naphthalene and the like, acrylic and methacrylic acids, esters, 'nitriles and amides such as acrylic acid, acrylonitrile, methacrylonitrile,- methyl acrylate, methyl methacrylate, butyl acrylate. methacrylamide and the like, and other vinyl compounds such as vinyl ketone, vinyl ethers, vinyl carbazole, vinyl iurane and. the like. Monomer mixtures of butadienes with other compounds group suchas vinylidene chloride and the like may also be used. All these monomers and monomer mixtures when polymerized or copolymerized in the manner herein described form high molecular weight linear polymers. when the conjugated butadiene is the monomer or is the predominant constituent of a monomer mixture such polymers. are rubbery in character and may be termed synthetic rubber.

Other monomers or monomer mixtures which are capable of undergoing addition polymerizations and which may be used in the process of thisinvention are the above-mentioned vinyl and iected by the redox cat: ysts-oi' this invention for various monomers and'monomer mixtures is illustrated in table I. In each case 'anemulsion o! 10 grams of the monomerin 25' cc. of a 2% aqueous solution of myristic acid which has been 85% neutralized with sodium hydroxide, and also containing .035 gram of hydrogen peroxide and .03 gram of a polymerization modifier is allowed to polymerize in a constantly rotated, sealed glass tube. As shown in the table, Dolymerizations are effected both with and without the i'urtheraddition of a redox system consisting of gram of sodium pyrophosphate and .01 gram of ferric pyrophosphate. The yield, time and tempera-.

ture recorded for each polymerization shows that the redox system allows the polymerization to proceedmore rapidly and at 'a lower temperature and at the same time produces higher yields. Tests on the polymerization products also show that a higher molecular weight, more linear and consequently'more desirable polymer is obtained.

- Table I Redo: Monomer systems Yield Time Temp.

' Percent Hours C. Butadiene 5.5 g Absent" 95 48 30 Acrylonitrile 4.5 g Present 23 30 v Butadiene 7.6 g. Absent. 95 136 30 Styrene 2.51..." Present. 100 66 30 Butadiene 7.5 g Absent... 92 48 30 Methacrylonitrile 2.5 g Present 100 28 30 Butadiene 7.5 g Absent. 86 144 30 Methyl methacrylate 2 Present 97 .74 30 Vinyl chloride g $1211; 38 g 33 Acrylonitrlle 10 g g f Absent" 90 48 40 5 {Present 01 44 35 sifying agent and with a polymerization modi-- fier. It is also possible to produce a similar increase in the rate of polymerization by using a redox system in emulsions containing various other polymerization initiators and emulsifying agents as well as various polymerization modiilers such as dialkyl dixanthogens, diaryl disulildes, thiuram disulfides and other sulfur containing compounds known to increase the solubility and plasticity of the polymer. Among the initiators which may be used with the redox systems are hydrogen peroxide, organic peroxides, barium peroxide, potassium persulfate, sodium perborate, potassium percarbonate and the like, and other polymerization initiators such as diazoaminobenzene and, sulfur dioxide. The redox systems of this invention may also be used advantageously in the polymerization of conjugated dienes carried out in presence of a peroxide and a peroxide activator such as sodium pyrophosphate, amino acids, and saturated or unsaturated fatty acids. Moreover, the redox systems'of this invention may be used to effect polymerizations which are carried out in the absence of an added initiator. the improvement effected by a redox system, so-, dium ferri pyrophosphate .075 g., in the emulsion polymerization of a mixture containing 4.5 g.

of acrylonitrile and 5.5 g. of butadiene emulsifled with 25 cc. of a 2% aqueous solution of 85% neutralized myristic acid, with various initiators and with no added initiator. The results show that the action of the redox system does not depend upon the presence of any particular polymerization initiator.

Although partially neutralized fatty acids are Table II' shows I ing agents including completely neutralized fatty acid soaps such as sodium oleate or sodium palmitate and hymolal sulfates or sulfonates such as sodium lauryl sulfate and sodium isobutyl sulfonate. When using redox systems which work best under conditions similar to those present in living cells such as adenylic acid pyrophosphate in presence of a heavy metal, it may also be desirable to add other emulsifying or solubilizing agents which are present in biological systems such as bile salts, proteins, or other organic colloids.

Since sodium ferri pyrophosphate is one of the preferred redox systems and since it will function under a variety of conditions, the results tabulated have been obtained using this particular redox system. However, similar results may be obtained with any of the redox systems included in the scope of this invention. The followin examples illustrate the use of other redox systems.

is polymerized for 20 hours at 30 C. A quantitative yield of a rubber-like butadiene acrylontrile copolymer is obtained. When using the same recipe without the sodium pyrophosphate cuprous chloride system, 48 hours are required to complete the polymerization.

Example II An emulsion containing: I Butadiene g 7.5 Methyl methacrylate g 2.5 Emulsifying agent (2% aqueous solution of 85% neutralized myristic acid) cc 25 Hydrogen peroxide (3 sol.) cc 1 1 Polymerization modifier g 0.03 Ferrous sulfate g 0.001 Sodium hypophosphite g 0.05

i polymerized at 30 C. An 89% yield of a rubber-like copolymer is obtained in 25 hours. Without ferrous sulfate and sodium hypophosphite, only an 81% yield is obtained in hours.

Example III An emulsion containing:

Bu'tadiene g 7.5 Styrene g 2.5

' Emulsifying agent (2% aqueous solution of neutralized myristicacid) cc 25 Hydrogen peroxide (3 /2% so1ution) cc 1 Polymerization modifier" g 0.03 Ferrous ferric lactophosphate g .01

is polymerized at30 C. An 81% yield of onpolymer is obtained in hours. Without ferrous ferric lactophosphate it requires 110 hours to produce only a 59% yield.

Although various embodiments of the invention have been herein disclosed, it is not intended that the invention be limited solely thereto for itwill I be obvious to those skilled in the art that many CH =C group and which undergoes in aqueous emulsion an addition polymerization to form a high molecular weight linear polymer, to polymerization in aqueous emulsion in the presence of a catalyst comprising a water-soluble heavy metal salt combined with a derivative of a phosphorusoxyacid selected from the class consisting of salts and esters of phosphorus oxyacids, the total concentration of the heavy metal salt and the said phosphorus oxyacid derivative being less than 2% by weight of the material polymerized and the concentration of the heavy metal salt being such.

that the polymerization proceeds more rapidly than in the absence of the heavy metal salt.

2. The method of claim 1 in which the material subjected to polymerization is a polymerizable conjugated butadiene.

-3. The method of claim 1 in which the material subjected to polymerization is a mixture of a polymerizable conjugated butadiene and at least one other compound which contains a group and is copolymerizable therewith in aqueous emulsion.

4. The method which comprises subjecting a mixture of a polymerizable conjugated butadiene and at least one other compound which contains a CHa=C group and is copolymerizable therewith in aqueous emulsion, to polymerization in aqueous emulsion in the presence of a water-soluble catalyst consisting of a water-soluble heavy metal salt combined with a pyrophosphate, the total concentration of the heavy metal salt and the pyrophosphate being less than 2% by weight ofthe material polymerized, and the concentration of the heavy metal salt being such that the polymerization proceeds more rapidly than in the absence of the heavy metal salt.

5. The method of claim 4 in which the watersoluble heavy metal salt is a salt of a metal occurring in the 6th to 12th positions of the first long period of the periodic table.

6. The method of claim 4 in which the catalyst 4 is a mixture of an alkali metal pyrophosphate combined with a pyrophosphate of a metal occurring in the 6th to 12th positions of the first long period of the periodic table.

7. The method of claim 4 in which the material polymerized is a mixture of butadiene-1,3 and at least one copolymerizable vinyl compound and the catalyst is a mixture of an alkali metal pyrophosphate and a pyrophosphate of a heavy metal occurring in group VIII and the first long period of the periodic table.

8. The method of claim 4 in which the material polymerized is a mixture of butadiene-1,3 and acrylonitrile and the catalyst is a mixture of an alkali metal pyrophosphate and an iron pyrophosphate.

unsaturated organic compound whichcontains a group and which undergoes in aqueous emulsion an addition polymerization to form a high molecular weight linear polymer, to polymerization in aqueous emulsion in the presence of a catalyst comprising a water-soluble complex compound or a heavy metal and a derivative of a phosphorus oxyacid selected from the class consisting of salts and esters of phosphorus oxyacids, the concentration of the said complex compound being less than 2% by weight of the material polymerized and such that the polymerization proceeds more rapidly than in the absence of the complex compound.

10. The method of claim 9 wherein the'material polymerized is a mixture 01' a polymerizable conjugated butadiene and at least one other compound which contains a 11. The method vwhich comprises subjecting a polymerizable material consisting of at least one unsaturated organic compound which contains a group and which undergoes in aqueous emulsion an addition polymerization to form a high molecular weight linear polymer, to polymerization in aqueous emulsion in the presence of a catalyst comprising a water-soluble complex compound containing a heavy metal atom and a pyrophosphate radical present in the same molecule, the concentration of the said complex compound being less than 2% by weight of the material polymerized and such that the polymerization proceeds more rapidly than in the absence of the complex compound.

12. The method of claim 11 wherein theme. terial polymerized is, a mixture of a polymerizable conjugated butadiene and at least one other compound which contains a group and is copoiymerizable therewith in aque' sion in the presence of a catalyst comprising a water-soluble complex compound containing an atom of a heavy metal occurring in the 6th to 12th positions of the first long period of the periodic table and a pyrophosphate radical, the concentration of the said complex compound besubjecting a ing less than 2% by weight of the material polymerized and such that the polymerization proceeds more rapidlythan in the absence oi the complex compound.-

15. The method of claim 14 wherein the heavy metal is a heavy metal occurring group VIII and the first long period of the periodic table.

16. The method of claim 14 wherein the catalyst is an alkali metal heavy metal pyrophosphate in which the heavy metal is a metal occu n in group VIII and the riodic table.

17. The method of claim 14 wherein the material polymerized is a mixture or butadiene-1,3 and acrylonitrile and the catalyst is an alkali metal iron pyrophosphate.

- 18. The method which comprises subjecting a polymerizable material consisting of at least one unsaturated organic compound which contains a Patent No. 2,380,473. I

first long period of the pe- Certificate. of Correction WILLIAM D. STEWART group and which undergoes in aqueous emulsion an addition polymerization to form a high molecular weight linear polymer, to polymerization in aqueous emulsionin the presence oi! a catalyst comprising a water-soluble complex compound complex compound is an iron lactophosphate.

wnmmur n. STEWART.

July 31, 1945'.

It is hereby certified that errors appear in the printed specification of the above 7 numbered patent requiring correction as follows: Page 3, second column, line 7, 1 after isobutyl insert naphthalene; pa e 5, first column, line 6, claim 15, after Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the occurring insert in; and that the sai Patent Oflice.

Signed and sealed this 4th day of June, A. D. 1946.

LESLIE FRAZER, I

First Assistant Uomm'issioner of Patents.

ing less than 2% by weight of the material polymerized and such that the polymerization proceeds more rapidlythan in the absence oi the complex compound.-

15. The method of claim 14 wherein the heavy metal is a heavy metal occurring group VIII and the first long period of the periodic table.

16. The method of claim 14 wherein the catalyst is an alkali metal heavy metal pyrophosphate in which the heavy metal is a metal occu n in group VIII and the riodic table.

17. The method of claim 14 wherein the material polymerized is a mixture or butadiene-1,3 and acrylonitrile and the catalyst is an alkali metal iron pyrophosphate.

- 18. The method which comprises subjecting a polymerizable material consisting of at least one unsaturated organic compound which contains a Patent No. 2,380,473. I

first long period of the pe- Certificate. of Correction WILLIAM D. STEWART group and which undergoes in aqueous emulsion an addition polymerization to form a high molecular weight linear polymer, to polymerization in aqueous emulsionin the presence oi! a catalyst comprising a water-soluble complex compound complex compound is an iron lactophosphate.

wnmmur n. STEWART.

July 31, 1945'.

It is hereby certified that errors appear in the printed specification of the above 7 numbered patent requiring correction as follows: Page 3, second column, line 7, 1 after isobutyl insert naphthalene; pa e 5, first column, line 6, claim 15, after Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the occurring insert in; and that the sai Patent Oflice.

Signed and sealed this 4th day of June, A. D. 1946.

LESLIE FRAZER, I

First Assistant Uomm'issioner of Patents. 

